Drainage Area Planning (DAP)

Drainage Area Plans (DAP) are used by Water Companies to assess the performance of their sewerage networks with respect to hydraulic, structural, operational and environmental performance criteria. The DAP also considers sewerage improvement options with 5 to 25 year design horizons to assist Water Companies in their investment planning to meet regulatory and customer service objectives.

Clear offers a comprehensive range of sewerage and drainage area planning services. Our aim is to provide the highest level of service to our clients through our skilled and experienced team of catchment planners, modellers, engineers and technicians using the best modern tools and methods. We recognise that the successful management of a sewerage system requires not just engineers, but also skilled catchment planners and drainage planners.

Our staff have extensive professional and technical experience in drainage area planning and in the design, construction and rehabilitation of sewerage systems. Our expertise includes studies ranging from rural village communities to major cities and large trunk sewer macro models encompassing complete catchment areas.

These studies cover a range of catchment problems including flooding and the routing of flood flows, polluting CSOs, in-sewer silt build up, catchment growth and land drainage issues. Through the use of hydraulic models, historical data and operational records, Clear can identify catchment needs and develop outline solutions.

We are experienced in carrying out structural and operational analyses, and amalgamating data from a variety of sources to produce robust drainage area plans. We are at the cutting edge of applying new technology to drainage area planning and sewer modelling, and are able to provide innovative solutions to wastewater problems.

Clear has been involved in the delivery of large programmes of Drainage Area Planning and hydraulic model builds in AMP4 as a Framework Partner to Severn Trent Water (39 DAPs), Anglian Water (11 DAPs) and United Utilities (9 Model Maintenance Studies). We have undertaken studies on catchments up to 500,000 population including Norwich, Derby, and Coventry.

 

We have been proactive in the development of sewer modelling and Drainage Area Planning specifications and guides for various water companies, ensuring that these are following most recent best practice and incorporating new modelling and procedural developments.

Clear has experience in risk based approaches to Drainage Area Planning, and is familiar with the concepts outlined in the Capital Maintenance Planning Common Framework and the recent SRM5. Clear has developed tools to allow Drainage Area Planning to be undertaken relating level of service to risk (likelihood and consequence) rather than the more straightforward performance defined approaches.

Clear has developed risk based flood mapping approaches, and various scenario testing methods such as emergency planning, pumping station failure impact analysis and sewer blockage analysis. Clear has experience in presenting these risk outputs as annualised damage costs.

We have recently undertaken a number of detailed model assessments, where enhanced Type III models have been constructed specifically for detailed design purposes. We frequently work in tandem with designers and undertake model analyses in parallel to scheme design

We have extensive expertise in the following key areas of Drainage Area Planning:

  • Data collection
  • Digital mapping and GIS
  • Survey planning and supervision
  • Flow survey management
  • Model build and verification
  • Hydraulic analysis
  • CSO performance analysis
  • Infiltration assessment
  • Structural and Operational analysis
  • Needs identification and reporting
  • Flood risk mapping
  • Emergency planning
  • Optioneering
  • Feasibility studies